final report - pennsylvania state universitymitchell e. peters/mechanical option/apr. 7, 2010 10/11...

Apr. 7, 2010

10/11

Final Report Alternative Systems Analysis

Army National Guard Readiness Center Addition Arlington, Va.

Mitchell E. Peters Mechanical Dr. Bahnfleth – Advisor

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Mitchell E. Peters/Mechanical Option/Apr. 7, 2010

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Table of Contents

Table of Contents________________________________________________3

Acknowledgements______________________________________________6

1.0 Executive Summary__________________________________________ 7

2.0 Existing Conditions___________________________________________8

2.1 Introduction________________________________________________8

2.2 Design Objectives and Requirements_______________________________8

2.3 Site and Budget______________________________________________8

2.4 System Initial Cost____________________________________________8

2.5 Lost Space_________________________________________________ 9

2.6 Energy Sources______________________________________________9

2.7 Design Air Conditions_________________________________________10

2.8 Equipment Summaries________________________________________10

2.9 System Operation____________________________________________13

2.9.1 Schematics__________________________________________13

2.9.2 Air Side____________________________________________14

2.9.3 Water Side_________________________________________ 15

3.0 Previous Technical Report Information_______________________15

3.1 Ventilation Requirements_____________________________________15

3.2 Heating and Cooling Loads_____________________________________16

3.3 Annual Energy Use__________________________________________19

3.4 LEED Analysis for the Mechanical System____________________________21

3.5 Energy and Atmosphere________________________________________21

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3.6 Indoor Environmental Quality____________________________________22

4.0 Overall Evaluation___________________________________________23

5.0 Proposed Alternative System_________________________________24

5.1 System Optimization__________________________________________24

5.1.1 DOAS________________________________________________24

5.1.2 Active Chilled Beams____________________________________25

5.2 Breadth Topics _________________________________________________26

5.2.1 Construction Management_______________________________26

5.2.2 Acoustical Breadth_______________________________________26

5.3 Tools for Analysis_______________________________________________26

5.4 Basis for Comparison____________________________________________27

5.4.1 Initial Cost__________________________________________27

5.4.2 Lifecycle Cost___________________________________________27

5.4.3 Indoor Air Quality_____________________________________27

5.4.4 Energy Use_____________________________________________27

5.4.5 Environmental Impact____________________________________28

6.0 DOAS_______________________________________________________28

6.1 Preliminary Analysis_____________________________________________28

6.2 Active Chilled Beams_____________________________________________29

6.3 DOAS Fan Coil Unit______________________________________________29

6.4 System Modeling_______________________________________________30

6.5 Results______________________________________________________31

7.0 Construction Management___________________________________33

8.0 Acoustical___________________________________________________34

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8.1 SCIF Specifications______________________________________________35

8.2 SCIF Acoustical Specifications_____________________________________36

8.3 Analysis and Results_____________________________________________38

9.0 Final Conclusion and Discussion of Results____________________39

References_____________________________________________________40

Appendix A: Tabulations________________________________________41

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Acknowledgments

The Pennsylvania State University Architectural Engineering Faculty Advisor: William Bahnfleth, Ph.D., PE Sponsor: Turner Construction Main Contact: Arne Kvinnesland, LEED AP Special Thanks to my friends and family for their continuing support. Brittany Baker for keeping me on track and focused, you were always there. JP Peno, Dan Saxton, Sara Pace, and Bryan Pieffer for being my AE group

throughout the five years.

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1.0 Executive Summary

The following report has been prepared to determine the benefits of implementing a Dedicated Outdoor Air System (DOAS) in conjunction with Active Chilled Beams (ACB) and DOAS Fan Coil Units. This system will be placed with the current hydronic VAV system and compared with the as designed documents. To begin, an overview of the building is provided. The existing mechanical system design as well as operational forecasts were analysised closely to provide a benchmark for comparison. The proposed system is then described followed with the actual design.

The redesign started with a summary of preliminary research on the units which would be used. Using Trane TRACE 700 block analysis and required ventilation rates and design temperatures to determine the buildings loads. With this determined, humidity ratios as well as cooling coil loads. The sensible cooling capacity for the supply was determined and subtracted from the total sensible load to find the ACB load. It was determined that 1,277 2’x4’ ACB’s would be needed. Resizing of the existing mechanical system was conducted and cost analysis performed. Though information was limited, a payback of 25 yrs was determined. Energy analysis showed this system provided a 24% reduction in load, however, the system and this payback could be undesirable for the owner. As this is a Government project, this might not be the case. An analysis on the impacts on cost and scheduling was investigated to determine how this system would affect construction. The nature of the building offered interesting acoustical studies, one particular space (SCIF), required acoustical isolation for security purposes.

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2.0 Existing Conditions

2.1 Introduction

The ArNG Readiness Center addition will function as an administrative headquarters in conjunction with the existing complex on site. There are a total of 8 floors, 3 below grade and 5 above. The building houses open office spaces, fitness facilities, an auditorium, and Joint Operations Center to name a few. The building was design mechanically for efficiency and occupancy use in mind.

2.2 Design Objectives and Requirements

When the designers sat down to analyze the future mechanical systems for the ArNG building there were two main focuses. Meeting and or exceeding the necessary ASHRAE standards while striving for an energy efficient design. This energy efficient design should warrant LEED points for the goal of being certified LEED Silver. From the ASHRAE standards the ArNG building must meet thermal comfort as well as IAQ stipulations. To meet these requirements a simple VAV system was specified to condition the spaces. These VAV systems are used in conjunction with high efficiency chillers with cooling towers, boilers, and efficient CRAC units for high demand spaces.

2.3 Site and Budget

The site of the ArNG building is located in Arlington, Virginia. The building is owned by the Army National Guard and the facility is to be an expansion of an existing facility on the site. The site is located on a very soft and spongy soil making it difficult for the foundation system. This is due to an unknown source of water entering the site from several sides. Current information is being obtained on budget information but the initial project budget was roughly $89 million with a budget of $9.7 million for the mechanical system. This is protected due to the government use of the building and that it is still under construction.

2.4 System Initial Cost Original cost for the mechanical system is unknown but othe budget was $9.7 million, any redesign should be under this amount. Only the cost per square foot could be procured at this time.

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2.5 Lost Space There is quite a large amount of lost space as a result of mechanical equipment. There are a total of 8 floors with three of these floors being underground. The underground floors are labeled as follows: 3P, 2P, and 1P. These floors have one large mechanical space which houses a single air handling units (AHU) with two subsequent mechanical spaces. Level 2P has a mechanical mezzanine which holds 5 AHU's. As for the above ground levels labeled 1T, 2T, 3T, 4T, and 5T each have one mechanical space housing a single air handling unit. These spaces house all of the mechanical shafts and therefor there is no need to account for any other lost space. The lost space in square feet is broken down by floor in Table 1 shown below.

Level Lost Space (SF)

3P 819

2P 2662

1P 1672

1T 703

2T 703

3T 703

4T 699

5T 703

Mech. Penthouse 11591

Total 20,255

Table 1

2.6 Energy Sources The ArNG building has two sources of energy availably, delivered electricity and a natural gas line. Dominion Virginia Power is specified as the utility provider however the specifics rates cannot be produced. As a result, standard rates for Arlington, Va. were used and are shown in Table 2 below.

Arlington, Va. Utility Costs

Electricity (cents/kWh) on-peak 8.97

off-peak 6.07

Natural Gas ($/therm) 0.261

Table 2

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2.7 Design Air Conditions The buildings location was specified as Washington, D.C. which is different than the buildings actual location. Arlington VA. is very close to the D.C. area and should provide the best approximation for the model. ASHRAE Design conditions for Washington, D.C. can be found in Table 3 below, taken from the ASHRAE Handbook of Fundamentals 2009.

ASHRAE Design Conditions for Washington, D.C. (.4% and 99.6%)

Summer Winter

DB (oF) MCWB (oF) DB (oF)

82.1 65.9 20.8

Table 3

As for the indoor design conditions, the values utilized for the ArNG building model were specified by the designer. These values are given in Table 4 below.

Indoor Design Conditions

Heating DB 70oF

Cooling DB 75oF

Relative Humidity 50%

Table 4

2.8 Equipment Summaries

The ArNG building has multiple uses; as a result the mechanical system has to be able to handle the various types of loads. From this, 17 AHU's are specified throughout the floors which feed VAV units which are spread throughout the various spaces as needed. This system is supported through the use of CRAC units in spaces with higher thermal demands. This system has been proven adequate and efficient for buildings of similar use and is very practical in this situation. The AHU's and VAV terminals are supplied with chilled water by means of 2 chillers coupled with 2 cooling towers. Heating is done through hot water which is supplied by 5 gas fired boilers. To supply this water the use of pumps is extremely important. The majority of these pumps are variable frequency controlled. The following Tables 5-10 display the specifications for the AHU's (max and min design OA), chillers and cooling towers, CRAC units, boilers, and pumps.

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Air Handling Unit Schedule

Unit Max/Min OA CFM Supply Fan CFM

AHU-3P-A1 2450 11800

AHU-3P-B1 1200 9500

AHU-3P-B2 950 2900

AHU-3P-B3 275 1650

AHU-3P-B4 900 12000

AHU-3P-B5 900 12000

AHU-2P-A1 2140 11800

AHU-1P-A1 2410 13400

AHU-1P-A2 0 9100

AHU-1P-B1 650 5700

AHU-1P-B2 4250 5400

AHU-1P-B3 1500 6400

AHU-1T-A1 1550 11900

AHU-2T-A1 1550 11900

AHU-3T-A1 1550 11900

AHU-4T-A1 1550 11900

AHU-5T-A1 1550 12600

Table 5 Air handling unit schedule depicting supply air flow as well as Outdoor Air usage.

Centrifugal Chiller Schedule

Chilled Water Condenser Water

Unit Capacity

Ton Flow GPM EWT 0F LWT 0F Ft. H2O Flow GPM EWT 0F LWT 0F Ft. H2O

CH-1 400 800 56 44 20 1200 85 95 20

CH-2 400 800 56 44 20 1200 85 95 20

Table 6 Chiller Schedule with flow rates and entering and leaving wet bulb temperatures specified.

Cooling Tower Schedule

Unit Flow GPM Fan HP EWT 0F LWT 0F

CT-1 1200 25 95 85

CT-2 1200 25 95 85

Table 7 Cooling Tower Schedule with entering and leaving wet bulb temperatures as well as flow rates.

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Computer Room Air Conditioner Schedule

Unit Total Capacity

(MBH) CFM

CRAC-1P-A1 245 9100

CRAC-2P-A1 140 6050

CRAC-2P-A2 140 6050

CRAC-3P-B1 72 2800

Table 8 CRAC unit schedule with specified cfm supply and cooling capacity.

Hot Water Boiler Schedule

Unit Type

Capacity (MBH)

GPM Supply Temp 0F Input Output

B-1 Natural Gas 1000 930 90 180

B-2 Natural Gas 1000 930 90 180

B-3 Natural Gas 1000 930 90 180

B-4 Natural Gas 1000 930 90 180

B-5 Natural Gas 1000 930 90 180

Table 9 Natural Gas fired boiler schedule showing its capacity and supply temperatures.

Pump Schedule

Unit Service Capacity GPM Head FT. Max HP Max RPM

CHWP-1 Chiller 800 105 30 1750

CHWP-2 Chiller 800 105 30 1750

CHWP-3 Chiller 800 105 30 1750

CWP-1 Cooling Tower 1200 80 30 1750



HWP-1 Heating Boilers 450 85 15 1750

HWP-2 Heating Boilers 450 85 15 1750

Table 10 Primary Pump schedule for water use in the ArNG building cover all chillers, cooling towers, and boilers.

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The actual system operations will be covered in the next section and will describe how the various equipment work together.

2.9 System Operation

2.9.1 Schematics The following Figure 1 depicts the heating water system for the ArNG building

Figure 1 The following Figure 2 shows the chilled water system

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Figure 2 Figure 2 was taken from the design documents. A personal schematic had been drawn but the file had become corrupt. Such a schematic is being reproduced at this time and will be placed in an updated Tech. Assignment 3 on the CPEP website.

2.9.2 Air Side

The ArNG building utilizes a VAV system in which each unit is supplied by air from a corresponding AHU. The mechanical unit as a whole uses a Building Automation System (BAS). Such a system for example will control the variable frequency supply fans attached with the AHU’s making the system very efficient. Such control of these supply and exhaust fans also manage the building pressurization. There is a 100% supply of OA at all times while utilizing humidity and temperature sensors to meet both cooling and heating loads.

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2.9.3 Water Side Cooling System: The chilled water distribution system consists of three chilled water pumps with variable frequency controllers pumping chilled water through the evaporator of one or both chillers, the heat exchanger, and to the building loads. The system uses two pumps to achieve maximum flow with a third pump functioning as stand-by if needed. The required flow through the chilled water system is controlled by varying the speed of chilled water pumps and corresponding bypass valve. The flow to each chiller’s evaporator is monitored by a flow sensor in the chilled water supply branch. The chilled water by-pass valve has the ability to modulate to maintain minimum chilled water flow to each active chiller. Finally the variable frequency controllers (VFC) modulate the speed of the chilled water pumps which maintain the differential pressure at a designated set point. When OA temperature is at a low enough point, chilled water can be provided without the operation of the chillers. This is because the system contains a heat exchanger, working in conjunction with the condenser water system; known as a water side economizer. Heating System: The heating water distribution system consists of two heating water pumps with variable frequency controllers pumping water through any one of the five boilers and heating coils throughout the building. The system uses 1 pump for system flow and the second as a stand-by if needed. The required flow through the heating water system is controlled by varying the speed of the heating water pumps. The VFC’s are in place to modulate the speed of the pumps to maintain the differential pressure at a designated set point.

December 1, 2009

3.0 Previous Technical Report Information The following section on ventilations, heating/cooling loads, and energy use were covered in

previous Technical Reports one and two. ASHRAE Standard 62.1 and 90.1 analyses are repeated

in the following section as is the annual energy use or building load analysis.

3.1 Ventilation Requirements The purpose of section 6 of ASHRAE Standard 62.1 is to determine the minimum outdoor air intake rates based on occupancy type, floor area, and design population. Ventilation rates were calculated for a descriptive section of the building. The ArNG Building has several different

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types of occupancies varying from offices to training facilities. By picking critical zones of the building it should provide a good representation of the rest of the building. From this it is then possible to label the building for compliance or non-compliance of Section 6 of ASHRAE Standard 62.1. The zones which were checked for ventilation are shown in Figures 62.1-1 and 62.1-2.

3.1.1 Outdoor Air Flow Calculation Assumptions 1. Levels 2T and 1P were used to gather an accurate representation of the building as a whole. 2. Zone populations were tabulated based on table 6-1 in ASHRAE Standard 62.1.

3.1.2 Results(ASHRAE 62.1 section 6) The critical spaces found were both an elevator lobby located in relatively that same area of the building but at different levels. This was the maximum Zp value resulting from the large default population which ASHRAE specified in table 6-1. The supply air to these spaces ended up being too low as a result. Another interesting note is the amount of cfm’s for the primary supply for level 2T. The AHU for level 2T is specified to handle 11,900 cfm’s. The calculations are fairly near to this value showing the unit running at an efficient level.

3.1.3 ASHRAE 62.1 Conclusion From the above analyses it is safe to say that the ArNG building does a very good job of adhering to Section 5 and 6 of ASHRAE Standard 62.1. Areas for improvement would be to reanalyze Section 6 and try and account for the low ventilation rates for a few of the spaces. 3.2 Heating and Cooling Loads The program utilized for the ArNG building modeling was Trane Trace 700. This program was chosen above other such software due to its user interface and my prior experiences. Trace uses an 8760 hour analysis to determine design loads, performance, and energy consumption. To construct the building model, information was gathered from DMJM H&N/AECOM and corresponding engineers. To properly model the ArNG building, several assumptions were made as follows.

3.2.1 Assumptions

To simplify the modeling process while producing an accurate model, the building’s various spaces were first placed into blocks as shown earlier in this document.

The two centrifugal water-cooled chillers were modeled as a single unit in the cooling plant to simplify the model

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The façade was modeled in accordance to the specified U values for the design wall materials

All internal loads for the ArNG model were based off of space function and type. From this, activity and occupancy levels were determined and found to mainly revolve around moderate office specifications. As for the lighting and miscellaneous loads, these were specified by the engineers on the project and inserted into the model. Such internal loads can be found in Table 11 below.

Internal Lighting/Miscellaneous Loads

Function Lighting (W/SF Miscellaneous (W/SF)

Office 1 1.5

Conference 1 1.5

Control/Telecom 1 9

Corridor 1 0

Electrical/Data 1 12

Media 1 3.5

Storage 1 0

Mechanical 1 0

Warehouse 1 0

Table 11 It is important for the energy model to follow some standard schedules for lighting as well as occupancy. Such schedules better analyze the full impact of the above loads on the various spaces. It is unreasonable to state that each space will be used 24 hours a day at full capacity. As a result, Table 5 shows the breakdown of light usage and occupancy as a percentage during various hours of the day.

Lighting/Occupancy Schedules

Time Lighting

(%) Occupancy

(%)

Midnight-7am 0 0

7am-8am 40 30

8am-6pm 100 100

6pm-7pm 40 10

7pm-Midnight 0 0

Table 12

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3.2.2 Computed Load From the above assumptions the ArNG model was complete and the analysis was initiated. The systems referred to in Table 6 (1P, 2P, 3P, 1T, 2T, 3T, 4T, 5T) correspond to an individual air handling unit per floor. This is not that case as floors 1P and 3P utilize multiple units, however they were combined as a whole to simplify the model. The following Table 6 provides the results of the Trace analysis, summarizing the cooling Sf/ton, heating Btuh/SF, total supply air cfm/SF, and ventilation supply cfm/SF)

Computed Loads

System Area (SF)

Cooling (SF/ton)

Heating (Btuh/SF)

Supply (CFM/SF)

Ventilation (CFM/SF)

1P 58811 297.28 30.47 0.68 0.231

2P 58129 738.1 10.67 0.2 0.098

3P 55343 331.62 29.06 0.9 0.146

1T 18497 389.03 31.05 0.64 0.174

2T 18447 370.76 33.09 0.65 0.193

3T 18478 376.18 32.19 0.64 0.188

4T 18486 378.05 32 0.64 0.187

5T 18420 347.64 35.51 0.68 0.213

Table 13

3.2.3 Heating and Cooling Load Conclusion Due to the sensitive nature of the building, design loads could not be acquired without a certain level of clearance. The engineer on the project was unaware of a student analyzing the mechanical systems and when approached could not procure the necessary documentation at this time. If such documents could be procured during the remainder of the year it would then be possible to compare the above computed loads with that of the design. Only speculation is possible to the accuracy of the above analysis; however there is a high level of confidence in my work. The values acquired are all fairly consistent for the size and use of the building. Such areas which would lead to discrepancies would be the analysis method used such as block loading or a room by room method and the software used. Programs such as eQuest are fairly common in the industry and use a different interface than Trace.

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3.3 Annual Energy Use

The Trace model which was used for the load calculations was again used for the annual energy consumption analysis. The majority of the building is powered by delivered electricity, however there are several natural gas fired boilers on site. Because the ArNG building is a hopeful LEED silver design, it is very important to take advantage of the following information to produce the most efficient and environmentally friendly building as possible. 3.3.1 Assumptions To generate the most accurate representation of the building which is to be built, the following analysis was based entirely off of the efficiencies and equipment specified by the engineers on the project. A Standard schedule of rates was established to showcase the peak, mid-peak, and off-peak hours for usage. This is shown in Table 14.

Schedule Rates

Time Rate

Specification

11pm-7am off-peak

7am-8am mid-peak

8am-6pm peak

6pm-11pm mid-peak

Table 14

3.3.2 Annual Energy Consumption (Modeled) The ArNG building has not had an energy analysis performed from what I have researched. After talking with my contact he disclosed such information would be available once the systems could be tested in the field. The results from the Trace energy analysis for consumption can be found in the following Table 15.

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Annual Energy Consumption(Modeled)

Electric (kWh) Gas (kBtu)

Heating 4,810 6,320,662

Cooling 1,406,332

Lighting 2,023,751

Pumps 415,511

Fans 1,294,561

Table 15 Majority of energy use is from lighting at 31.1 percent of the total building energy. Heating provided 29.2 percent and cooling contributed 21.6 percent to the total. These values can be broken down further to view individual contributions due to various parts of the system and such analysis shows large consumptions by receptacles and data/com centers. It would be extremely interesting to compare these results to that of the ArNG building design and will be done when the appropriate documents can be determined and released. Table 16 below is a breakdown by month for energy consumption. It is shown how drastic heating and electrical demands can vary by season. Electrical demands peak in the summer due to its use for the cooling systems and Natural gas demands peak in the winter due to its particular use for heating.

Table 16 Along with the above monthly breakdown, it is more pertinent to see a visual representation of the monthly energy consumption. Figure 3 below clearly shows the peaks for summer and winter heating/cooling respectively.

Electricity

January Feburary March April May June July August September October November December

On-Pk Cons. (kWh) 321,317 291,975 350,933 366,752 430,715 454,871 491,895 470,658 424,473 378,624 349,573 332,411

On-Pk Demand (kW) 473 486 546 582 663 745 783 753 692 584 563 504

Natural Gas

On-Pk Cons. (kWh) 11,441 10,375 7,152 4,370 2,294 2,031 1,406 1,771 2,437 4,447 5,786 9,036

On-Pk Demand (kW) 22 21 15 10 5 4 3 4 5 10 12 18

Water

Cons. (1000gal) 151 144 305 440 780 1,017 1,191 1,062 821 451 348 202

Monthly Energy Consumption

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Figure 3

3.4 LEED Analysis for the Mechanical System A LEED analysis was performed on the ArNG building using LEED-NC 2.2 (New Construction). From this LEED version there are two categories to be had for mechanical systems of a building: Energy and Atmosphere, and Indoor Environmental Quality. Energy and Atmosphere has 3 prerequisites with 6 potential credit earning categories. Indoor Environmental Quality has 2 prerequisites with 5 potential credit earning categories.

3.5 Energy and Atmosphere (EA) EA Prerequisite 1 is to have fundamental commissioning of the building energy systems. This involves verification that the building's energy systems are installed, calibrated and performing according to the design. This is currently being performed and thus this prerequisite is obtained.

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EA Prerequisite 2 involves the minimum energy performance required for the building. This is done by establishing the minimum level of energy efficiency for the proposed building and system. A baseline was established for this design thus complying with this prerequisite. EA Prerequisite 3 is a requirement to manage refrigerant use in the building. This requires that no CFC based refrigerants can be used in the building. The ArNG building has selected all equipment which refrains from using CFC refrigerants and thus is in compliances. 20 EA Credit 1 is established to reduce environmental and economic impacts associated with excessive energy use. The ArNG building is project to save around 11% of energy use of its baseline. From this, the building receives 1 point. EA Credit 2 looks for potential use of on-site renewable energy or self-supplies to reduce environmental and economic impacts from fossil fuel usage. The ArNG building has no know sources of on-site energy and thus receives no points out of a potential 1-7. EA Credit 3 requires beginning the commissioning process early in the design process while establishing additional activities to verify system performance after construction. The ArNG building receives 1 point under this category. EA Credit 4 covers refrigerant management. This is implemented to reduce ozone depletion and support early compliance with the Montreal Protocol while minimizing contributions to global warming. The total refrigerant impact per ton must be less than 100 which the ArNG building easily complies with. This is good for 1 point. EA Credit 5 is for measurement and verification to monitor energy consumption over time. The ArNG building is under construction. It can however be assumed that a plan for measurement and verification has been set in place and will be enacted when systems are up and running. Such a plan will award 1 point. EA Credit 6 encourages the use of renewable energy technologies on a net zero pollution basis. This requires that at least 35% of the buildings electricity is from renewable sources for at least two years. The ArNG building is not seeking to achieve this point.

3.6 Indoor Environmental Quality EQ Prerequisite 1 is to establish a minimum for indoor air quality (IAQ). This requires that ASHRAE standard 62.1 be met for IAQ. From the engineers analysis it was found that the ArNG building is in compliance with this prerequisite. From Technical Report 1 it was found that some spaces were non-compliance but this could be contributed to occupancy assumptions.

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EQ Prerequisite 2 is to control environmental tobacco smoke. The ArNG building is a non-smoking facility and is thus in compliance. Only EQ credits 1, 2, 6.2, 7.1, and 7.2 deal with the mechanical systems of the ArNG building and have thus been explored below. EQ Credit 1 is the monitoring of the outdoor air being delivered. This will allow for increased and sustained occupant comfort and well-being. The main requirement is that CO2 monitoring must be done in every densely occupied space. The ArNG building complies and is thus awarded 1 point. EQ Credit 2 is to increase ventilation which will improve IAQ for occupant comfort, well-being, and productivity. To increase ventilation there must be a compromise on energy consumption. To use the least amount of energy possibly, this was not considered for the ArNG building. EQ Credit 6.2 demands individual occupant control for thermal comfort. It requires that 50% of the building occupants be able to adjust the system to suit individual task needs and preferences. The ArNG building has several open office spaces which are feed by several VAV boxes. Some of these boxes however feed into conference rooms as well as the office spaces. From this it is determined that no points be awarded. EQ Credit 7.1 is design of thermal comfort which supports the productivity and well-being of building occupants. Based on the calculations done for EQ 7.1, Standard 55‐2004 is satisfied and 1 point is awarded. EQ Credit 7.2 is the verification and assessment of thermal comfort over time. This credit requires only the agreement that a thermal comfort survey be conducted within six to 18 months after occupancy. This awards 1 point to the ArNG building.

4.0 Overall Evaluation

From an overall standpoint, the mechanical system of the ArNG building seems to be fairly typical. It is not only efficient, but it seems to have been implemented in a timely and cost effective manner. The specified VAV system in conjunction with high efficiency equipment can satisfy nearly any kind of load thrown at it, that is if it has been implemented in the correct fashion. Being that that this building will function as a multi-use administrative office building, a VAV system is a fairly common solution for the mechanical system. The majority of the building is powered by delivered electricity, however there are several natural gas fired boilers on site. Although initial costs of the systems are still being explored, this system is fairly typical and should compare to a mid-rise multi use office building. The building utilizes 100% outdoor air (OA) which must be considered in these costs.

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As for the total annual consumption for the ArNG building, it was found to be 4,664,299 kWh for electricity and 6,320,662 kBtu for gas. The majority of these values arise from space heating of the tower and lighting fixtures throughout the building. From the above energy consumption, it was determined that the ArNG building will require around $1.95/SF a year to operate. The system is fairly common and thus typical building engineers will be familiar with its operation and maintenance. A VAV design is fairly simple and when in place with the BAS controls allow for high efficiency.

5.0 Proposed Alternative Systems The ArNG mechanical system is sufficient for this type of building use. It meets the LEED certifications while complying with ASHRAE Standards 62.1 and 90.1. There is however always room for improvement. The following alternative solutions are intended to reduce operating costs which is directly tied to increasing efficiency. Load reduction with DOAS and implementation into a GSHP system can be compared with the current system showcasing the potential gains.

5.1 System Optimization 5.1.5 Dedicated Outdoor Air System

The first alternative is known as a DOAS. With this type of system 100% outdoor air (OA) is used to ventilate a space. Because only OA is being used for ventilation, duct sizes can be significantly reduced in comparison to that of a standard VAV system. It is important to note that sensible and latent loads must be treated separately. This type of system is often coupled with fan-coil units, chilled beams, and other methods to meet remaining sensible loads within the space. Specifically, latent loads will be handled at the AHU. The DOAS setup consists of the following: an enthalpy wheel, AHU’s, coupled with some form of terminal units. With any system there needs to be some form of regulations and ASHRAE Standard 90.1 stipulates that preconditioning the air is a requirement. This system uses 100% OA for the supply and thus has no mixing requiring total heat recovery. A standard VAV system mixes OA with return air (RA) accomplishing preconditioning before the coils. The heat recovery unit utilized uses energy from within the building in a process with the OA. There are many potential advantages, some of which have been touched on previously. First and for most, this type of system has the ability to increase a buildings overall efficiency. There are several was this is accomplished. Reduced supply air requirements and decoupling of heating and cooling from ventilation air provided substantial gains. This however is only the tip

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of DOAS. Indoor air quality can remain the same or even increase while downsizing ductwork and fans. The system specified currently generally uses more OA than is required by DOAS. The VAV system can have trouble properly ventilating all spaces with fresh air, DOAS does not have this problem. This large amount of OA requires significant conditioning in both summer and winter which accounts for large energy consumption. Mechanical space requirements are reduced and impacts initial construction costs. A DOAS system has the ability to achieve greater efficiency while treating 100% of the latent loads in the space. DOAS also handles 100% of the OA load requirements and a potentially large amount of the sensible loads.

5.1.2 Active Chilled Beams This above system will be accompanied with the use of CRCP (chilled beams) and also fan coil units. With chilled beams there are two applications, passive and active and work by natural forces due from air temperature gradients. This allows for natural air movement and a reduction in fan energy. Active chilled beams are connected to the DOAS for airflow from the unit. The beam itself activates air circulation after mixing with ventilation air. Passive chilled beams do not provide the mixing with the ventilation air. The room air induction is for cooling purposes, the ventilation air is provided via alternative methods. The major issues which can arise from the use of chilled beams is the general inexperience which contractors and maintenance workers. Also of significant importance is environment control to ensure condensation does not occur within the building and in possibly sensitive areas. With chilled beams it can become an issue involving spaces which require both cooling and heating. Such spaces are often located around the buildings perimeter and would potentially require another technology in conjunction with the DOAS. This is a very simple solution using FCU’s which can contain both a heating and cooling coil, non-condensing, within the unit itself. This type of technology is fairly typical and would have little installation and maintenance issues. These units can be placed where appropriate to cut down on zone load costs and handle more than one space at a time. Though more research is pending, utilizing a DOAS setup for the ArNG building should have substantial savings in energy in both fan and chiller energy. It is unreasonable to assume that this system wouldn’t use more energy in some area. Basis for comparison is in an upcoming section.

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5.2 Breadth Topics

5.2.1 Construction Management

The proposed mechanical system alternatives will result in substantial scheduling issues and thus will impact costs. Using RS Mean information it will be possible to determine scheduling and cost impacts for the new system. This will greatly affect construction times and will be determine continuation with construction. Cost estimation due to these schedule changes will also need to be analyzed in an effort to fully understand the impact such a system would induce.

5.2.2 Acoustical An interesting aspect of the ArNG building is directly tied to its function. It is an Army National Guard Readiness Center, as a result the building has some very distinct functions which require various considerations. One such function is that of its SCIF space. These areas are classified requiring very special care when it comes to privacy. The building as a whole is mainly office spaces, but on the lowest level of the building these sensitive areas can be found. The function of these spaces are for conferencing between various government organizations and in an emergency will be used in a part, with other centers around the country, to run the United States. It is clear of the importance of these spaces and as a result they need to be heavily isolated from the spaces surrounding them. From this it is proposed to conduct an acoustical analysis of these spaces. The acoustical requirements of such a space will be studied first. Then, current sound isolation measures which have been designed will be studied in an effort to determine possible room for improvement. From there it will be possible to propose alternative acoustical systems to either, provide better sound isolation from the corridors and other spaces or accomplish the same isolation with new materials in a more cost effective manner.

5.3 Tools for Analysis

5.3.1 Energy Modeling

One of the most influential tools at the disposal of a mechanical engineer is the ability to create energy models. With each potential alternative system, it is important to analyze all cost information as well as monthly and annual energy use. To generate the above information, energy modeling is a necessity. Trane TRACE, Carrier’s HAP, Energy Plus, and eQuest are all viable modeling software but each have their limitations. Though familiarity with Energy Plus

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and eQuest are limited they should be considered to determine which above program offers the best accuracy in modeling. First it will be necessary to analyze and model the load reduction efforts. It is vital that this particular model be as accurate as possible, as this will determine the validity of the remainder of the new design efforts. Trane Trace will be my program of choice and I know it has the capability to model a DOAS design. Once this data is collected it will be cross-checked against know commercial buildings energy usage.

5.4 Basis for Comparison

When considering options for redesign of a system, it is important to lay the guidelines for determining whether a redesign is an improvement. The following are the criteria used to meter the success of the alternate system analysis:

5.4.1 Initial Cost

Initial Costs is what the Owner can visible see upfront. It is the most critical aspect which must be analysis for feasibility on a project. This cost must be studied closely along with the operating future of the building. As the ArNG building will be in operation for many decades to come, it is reasonable to design economically now, to save in the future.

5.4.2 Lifecycle Cost

With a baseline system established, along with maintenance cost information, the Lifecycle Cost will truly show which system operates economically.

5.4.3 Indoor Air Quality

The office spaces will be most impacted by the implementation of the new system. As a result IAQ of these spaces will be compared with the baseline VAV system.

5.4.4 Energy Use

Using energy modeling, and holding indoor thermal comfort constant, the two systems can be compared to ensure a comfortable environment can be provided.

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5.4.5 Environmental Impact This is a very important aspect of the analysis. This impact will be assessed based on the amount of energy used. If such use is lowered, the negative affects on the environment should be reduced as well.

6.0 Dedicated Outdoor Air Systems

6.1 Preliminary Analysis

The first alternative is known as a DOAS. With this type of system 100% outdoor air (OA) is used to ventilate a space. Because only OA is being used for ventilation, duct sizes can be significantly reduced in comparison to that of a standard VAV system. It is important to note that sensible and latent loads must be treated separately. This type of system is often coupled with fan-coil units, chilled beams, and other methods to meet remaining sensible loads within the space. Specifically, latent loads will be handled at the AHU. The DOAS setup consists of the following: an enthalpy wheel, AHU’s, coupled with some form of terminal units. With any system there needs to be some form of regulations and ASHRAE Standard 90.1 stipulates that preconditioning the air is a requirement. This system uses 100% OA for the supply and thus has no mixing requiring total heat recovery. A standard VAV system mixes OA with return air (RA) accomplishing preconditioning before the coils. The heat recovery unit utilized uses energy from within the building in a process with the OA. There are many potential advantages, some of which have been touched on previously. First and for most, this type of system has the ability to increase a buildings overall efficiency. There are several was this is accomplished. Reduced supply air requirements and decoupling of heating and cooling from ventilation air provided substantial gains. This however is only the tip of DOAS. Indoor air quality can remain the same or even increase while downsizing ductwork and fans. The system specified currently generally uses more OA than is required by DOAS. The VAV system can have trouble properly ventilating all spaces with fresh air, DOAS does not have this problem. This large amount of OA requires significant conditioning in both summer and winter which accounts for large energy consumption. Mechanical space requirements are reduced and impacts initial construction costs. A DOAS has the ability to achieve greater efficiency while treating 100% of the latent loads in the space. DOAS also handles 100% of the OA load requirements and a potentially large amount of the sensible loads. Trane Trace was used to model DOAS with a total enthalpy wheel for latent conditioning. The results which were collected correlated with the findings of several works, in which 100% of

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space latent loads, 100% of OA latent loads, 30% of total sensible load with total enthalpy wheel employed, leaving only 40% of design chiller load to be picked up. Though there are several limitations within the Trace program on DOAS, the results correlate nicely with the before mentioned percentages.

6.2 Active Chilled Beams (ACB)

The application of Active Chilled Beams is basically and induction unit. By using air at varying temperatures, and the natural buoyancy of air, flow can be established. By using high pressure nozzles, turbulent flow can be established to aid in mixing. Better mixing allows for warmer water temperatures in comparison to standard VAV (Approx 10-15 deg F increase). There are some disadvantages of Active Chilled Beams. Heating issues can arise and often require perimeter heating, also inexperience of contractors as well as maintenance doesn’t allow for full potential. The threat of condensation is also always a real possibility, but can be avoided when handled correctly. Figure 4 is an example of an Active Chilled Beam.

Figure 4

6.3 DOAS Fan Coil Unit

DOAS Fan coil units are another possibility which must be explored. ACB fall short for heating a space, but these units can handle those loads. This type of technology is common, so contractors and maintenance staff would have no trouble installing and maintaining. DOAS FCU’s allow for much lower zone costs. As stated before, ACB’s need to be used in conjunction with some form of perimeter heating. These systems would work very well with such an application. A single unit can heat, cool, and provide necessary ventilation air. Another positive is that these units can serve more than one space where as ACB’s cannot.

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6.4 System Modeling

To begin modeling this system it was first necessary to determine new design temperatures. From substantial research it was clear that standard dry blub temperature for ACB’s can be a few degree’s higher than necessary for convention VAV. The resulting temperture for cooling is now 77 deg F with 50% RH and a resulting dew point of 57.3 deg F. It is very important that the ACB’s are maintained above this temperature. If the necessary temperature difference for the beams and water temperature was on average 15 deg F, this gives a value of 62 deg F for the beams which is above the dew point. Using Trane Trace, two variations where utilized using DOAS. First was DOAS with strictly ACB. With this system wall heating units where needed to handle additional heating requirements. A total enthalpy wheel, as stated before, was specified, though only effectiveness could be imputed. Next DOAS Fan Coil Units where implemented. These were modeled as induction units with 4 pipes due to their similar construction and operation. The following Figure 5, shows a DOAS set up with ACB.

Figure 5

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Equations of particular importance are as follows: Supply Humidity Ratio

Sensible Load

Cooling Coil Load

Using these equations it was possible to determine all necessary aspects of the design. From this the critical space was determined to be the library on level 3T. Flow needed to be increased to this space to bump the humidity ratio from approx. 30.01 gr/lb dry air to the necessary 42.1 gr/lb of dry air. 6.5 Results

The proposed systems both have nearly the same potential reduction in required cfms. This reduction amount was 150,000 cfm which is approximately a 25% reduction. System CFM OA% Reduction

ACB 52,100 100 148700

FCU/ACB 50,200 100 150600

Existing VAV 200,800

Table 17

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First Cost. From this it is possible to cut out several system components. The main take away is 4 AHU which are no longer required due to the DOAS pick up. Also 8 FCU will no longer be required where specified throughout the tower levels. With this reduction in cfm, duct sizes are also significantly reduced. These savings are visible in Table 18, certain values were hard to find, such as RS Mean data on the AHU’s used in the ArNG building. Each was assumed to cost around $50,000. There will be an increase in pump requirements which needs to be analyized futher but would result in approximately $150,000 extra. The ACB’s required number 1,277 (2’x4’)at a price of approximately $400 per unit.

Initial Cost

Equip. Typ cost

AHU -200,000

VAV -18,434

FCU 0

Pump 167,264

Fan -15,645

ACB's 510,800

443,985

Table 18 The above systems however offer differences in energy usage. The main potential for savings can be seen in the heating load. There is an approximate 24% reduction when compared to the existing system. As for the cooling load, the FCU/ABC combination results in a higher load. Possible reasons could be modeling issues for lack of consistency with the true equipment. System Cooling(TONS) Heating(MBH)

ACB 656 4957.3

FCU/ACB 737 4803.2

Existing

VAV 728 6320

Table 19

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The next issue at hand is mechanical lost space. The prescribed ACB units need a place to go in the ceiling. As a result a study of this issue is as follows. The main area to focus on is the office space. Required ceiling area: ACB=100.0 W/SF Total Office: 6300 Tons x 3500W/Ton x 1/100 SF/W=220,500 SF required this is well under the 300,000 SF of available space. The Environmental impact will be significantly less with the implementation of this system. It was shown above that there will be approximately 24% reduction in energy demands. Because this system will be integrated into the current hydronic VAV set up, it is reasonable to conclude that impacts will be reduced equivalently to this reduction. Indoor Air Quality is of particular importance with this system. One of the major positives of a DOAS layout is the use of only outdoor air for supply. Even as loads decrease, this value remains 100%. With the DOAS FCU, 100% OA, there is still the terminal unit itself which uses dampers in an effort to condition the space. Any errors involved with this system can lead to poor ventilation and thus poor IAQ. As for the existing VAV system, recirculated air is utilized, as a result there is always the chance for contaminants. It is because of this that the DOAS ACB/FCU application would clearly lead to a much better IAQ than could be achieved with the current VAV system. In the end it was determined that the cost/SF of this mechanical system per year would drop from 1.95 to 1.83. Based on the above information, and the ability to cut out several AHU, the system will have a payback of 25 years.

7.0 Construction Management With the new proposed system it would be beneficial to get an idea of the construction impacts. To do so I used RS mean data, but such data is limited. For example, the ABC could not be included because they are not covered by the RS Mean data to this point. Estimating of various other system components was deemed necessary where appropriate, but the schedule should be fairly accurate to a point.

Table 20

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From this the time of install and cost is as follows in Table 21.

Table 21

8.0 Acoustical

The ArNG building provides several interesting areas mainly because of its purpose. It is

Readiness Center, and as a result contains certain rooms that are of a sensitive nature. One such

space is the SCIF, Sensitive Compartmented Information Facility, located on level 3P, the

deepest floor of the building. Figure 6 shows the SCIF area.

Figure 6

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8.1 SCIF Specifications

As with any sensitive Government area, there are several specifications which must be followed.

The idea of this type of area is as follows. A SCIF is an accredited area, room, group of rooms,

buildings, or installation where SCI may be stored, used, discussed, and/or electronically

processed. This space is accessible only to those individuals with proper clearance. The physical

security protection for a SCIF is intended to prevent as well as detect visual, acoustical,

technical, and physical access by unauthorized persons. One can see that this is to be a highly

secured space which, in the case of the ArNG building, will be used during times of crisis.

Doors

Only a single primary entrance is acceptable for an SCIF, but emergency exits are an exception.

All perimeter SCIF doors must be closed when not in use. These doors must be plumbed in their

frames and firmly fixed to the surrounding wall. Door frames must be of sufficient strength to

avoid improper alignment of door alarm sensors and improper door closure.

Door Construction Types: Selections of entrance and emergency exit doors is to be consistent

with SCIF perimeter wall construction. Some acceptable types of doors are:

a. Solid wood core door, a minimum of 1 3/4 inches thick.

b. Sixteen gauge metal cladding over wood or composition materials, a

minimum of 1 3/4 inches thick. The metal cladding shall be

continuous and cover the entire front and back surface of the door.

c. Metal fire or acoustical protection doors, a minimum of 1 3/4 inches

thick.

There are two entrances into the SCIF space of the ArNG building, these doors both have an

STC rating of 55. As stated above, only one is desirable, but the exception of requiring a second

exit for emergency purposes was necessary.

Walls

The ArNG building uses a permanent dry wall construction for this space, the criteria for this

wall type is given as follows:

The walls, floor and ceiling will be permanently constructed and attached to each other. To

provide visual evidence of attempted entry, all construction, to include above the false ceiling

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and below a raised floor, must be done in such a manner as to provide visual evidence of

unauthorized Penetration.

The ArNG building specifies welded metal mesh applied to all the studs in the walls underneath

the GWB. The idea being that if someone REALLY wanted to get in, they couldn’t just drill a

hole through a wall or break down a wall because of the mesh. This space is “technically”

soundproofed due to increased layers of drywall on the walls, 4 total throughout this area.

8.2 SCIF Acoustical Specifications

Acoustical Isolation

The walls separating the SCIF space from other areas is to be sealed or insulted with

nonhardening caulking. This will prevent persons located in adjacent passageways from

overhearing SCI discussions or briefings from within the space, taking into account the normal

ambient noise level.

If this caulking and insulation is not sufficient to attenuate voices or sounds from

within the SCIF, the next step is to raise the ambient noise level with the use of sound

countermeasure devices, controlled sound generating source, or additional perimeter

material installation.

Air handling units and ducts will be equipped with silencers or sound countermeasure

devices unless continuous duty blowers provide a practical, effective level of masking

(blower noise) in each air path. The effective level of security may be determined by

stationing personnel in adjacent spaces or passageways to determine if SCI can be

overheard outside the space.

SCIF Sound Group

It is first important to understand the reasons for the acoustical protection and what it is used to

stop. The acoustical protection measures and sound masking systems are designed to protect SCI

against being inadvertently overheard by the casual passerby, not to protect against deliberate

interception of audio. The SCIF’s ability to keep sound from escaping its enclosed area will be

rated using the Sound Transmission Class (STC). This is a single number rating used to

determine the sound barrier performance of walls, ceilings, floors, windows, and doors.

According to the Architectural Graphics Standards (AGS), it describes various types of sound

control, isolation requirements and office planning. The AGS established Sound Groups I

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through 4, of which Groups 3 and 4 are considered adequate for specific acoustical security

requirements for SCIF construction.

Sound Group I - STC of 30 or better. Loud speech can be understood fairly well.

Normal speech cannot be easily understood.

Sound Group 2 - STC of 40 or better. Loud speech can be heard, but is hardly

intelligible. Normal speech can be heard only faintly if at all.

Sound Group 3 - STC of 45 or better. Loud speech can be faintly heard but not

understood. Normal speech is unintelligible.

Sound Group 4 - STC of 50 or better. Very loud sounds, such as loud singing, brass

musical instruments or a radio at full volume, can be heard only faintly or not at all.

These STC values were determined desirable based on STC Ratings were obtained from

Architectural Acoustics by Marshall Long for the calculation of the different of wall types.10

With the ArNG building and its SCIF space, it is desired to have an STC of 50 or better, placing

it in Group 4. It is also stipulated that if the SCIF is compartmentalized, the dividing walls must

meet Group 3 requirements.

Sound Masking and Stand-Off Distance

If standard construction practices can not meet the above sound groups of 3 or 4, sound masking

should then be applied. Protection against interception of SCI discussions may include use of

sound masking devices, structural enhancements, or SCIF perimeter placement.

Masking of sound which emanates from an SCIF area is commonly done by a sound masking

system. A sound masking system may utilize a noise generator, tape, disc or record player as a

noise source and an amplifier and speakers or transducers for distribution.

Placement of Speakers and Transducers

To be effective, the masking device must produce sound at a higher volume on the exterior of the

SCIF than the voice conversations within the SCIF. Speakers/transducers should be placed close

to or mounted on any paths which would allow audio to leave the area. These paths may include

doors, windows, common perimeter walls, vents/ducts, and any other means by which voice can

leave the area.

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For common walls, the speakers/transducers should be placed so the sound optimizes acoustical

protection.

For doors and windows, the speakers/transducers should be close to the aperture of the window

or door and the sound projected in a direction facing away from conversations.

Once the speakers or transducers are optimally placed, the system volume must be set and fixed.

The level for each speaker should be determined by listening to conversations occurring within

the SCIF and the masking sound and adjusting the level until conversations are unintelligible

from outside the SCIF.

8.3 Analysis and Results

There a few methods to increase the STC of a wall. This mainly involves adding mass,

increasing or adding air space, and adding absorptive material within the partition.

The ArNG building has no specified sound masking equipment and relies on the wall. The

welded mesh core wall with 4 layers of GWB is more than enough to sound poof the space. This

is a clear example of adding mass. But could less layers be used in conjunction with sound

masking to save money.

According to Marshall Long, the wall construction for the ArNG building should provide an

STC of 56 or more. Figure 7 shows this wall construction.

Figure 7

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Figure 8 shows the benefits of using the before mentioned caulking material to prevent

flanking noise.

Figure 8 Using RS Mean data is was possible to determine the cost of the proposed wall system for the SCIF area. This space has a wall surface area of 2,420 SF. Using this information, the proposed wall costs approximately $12.02/SF. This isn’t unreasonable when acoustical panel walls can run upwards of $20/SF. By using only a single sheet of 5/8” GWB on both the interior and exterior, along with resilient channels, the wall STC would be around 44. This is right around the Sound Group 3 level and would fit well in this situation if it wasn’t desirable to be in group 4. This wall type would cost approximately $7.18/SF. This is a considerable savings of around $30,000. In conjunction with this lower STC wal,l a sound masking system could be cheaply placed. Such a unit can cover over 6,000 SF and would cost considerably less than 30,000 dollars in savings. With this in mind, I would recommend installing the wall as designed. This is a very sensitive area and not one which should take shortcuts on design. The higher STC wall will ensure no sound exfiltrations.

9.0 Final Conclusion and Discussion of Results

With the analysis of the proposed mechanical system in mind, it would be hard to decided between one or the other. The cost estimates and payback were not unreasonable, though it was surprising to see how little can be saved from making substantial changes.

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First cost calculations were difficult for lack of information. This building is for Government purposes, and as a result has some documentation which can not be procured. This type of building is a perfect candidate for DOAS and there leave further room for improvement which wasn’t touched in the scope of this paper. Reduced duct sizes, decreased maintenance, increased IAQ are all positives for implementing this type of system. In the end the VAV system as design would be the likely choice. It is the economical choice in most situations and without further comparisons, it would be difficult to back up DOAS further.

References

ASHRAE. 2005, 2005 ASHRAE Handbook‐Fundamentals. American Society of Heating Refrigeration and Air Conditioning Engineers, Inc., Atlanta, GA. ASHRAE. 2007, ANSI/ASHRAE, Standard 62.1‐2007, Ventilation for Acceptable Indoor Air Quality. American Society of Heating Refrigeration and Air‐Conditioning Engineers, Inc., Atlanta, GA. ASHRAE. 2007, ANSI/ASHRAE, Standard 90.1‐2007, Energy Standard for Building Except Low‐Rise Residential Buildings. American Society of Heating Refrigeration and Air‐Conditioning Engineers, Inc., Atlanta, GA. CostWorks. RSMeans 2009. Reed Construction Data. March 20, 2010. http://www.meanscostworks.com Jeong, Jae‐Weon, Stanley Mumma, and William Bahnfleth. "Energy Conservation Benefits of a Dedicated Outdoor Air System with Parallel Sensible Cooling by Ceiling Radiant Panels." ASHRAE Transactions. 109.KC‐03‐7‐1 (2003): 627‐636. Print. Mumma, Stanley. "Overview of Integrating Dedicated Outdoor Air Systems with Parallel Terminal Systems." ASHRAE Transactions. 107.AT‐01‐7‐1 (2001): 545‐552. Print.

http://www.meanscostworks.com/

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Appendix A: Tabulations

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final report - pennsylvania state universitymitchell e. peters/mechanical option/apr. 7, 2010 10/11...

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